摘要
利用超声波高频振荡效应与双脉冲电源特性电沉积法制备Ni-CeO2稀土纳米复合镀层。利用环境扫描电镜(E-SEM)及透射电子显微镜(TEM),分别对镀层的微观形貌与晶粒结构进行分析表征。分析时效热处理和纳米稀土CeO2掺杂对晶体结构转变、显微硬度、热裂纹产生与扩展机理的影响。研究表明:由于纳米尺度稀土颗粒"抢占"Ni晶粒长大的空间,限制其粗大,生成组织致密且具有非晶态结构的合金镀层;复合沉积的稀土能钉扎愈合开裂的大晶界;纳米稀土颗粒填充晶界间隙等并有效地阻止裂纹源的萌生与扩展;经过500℃×2 h效热处理后,形成NiCexO1-x(0<x<0.5)等合金固溶体化合物并得以扩散互熔及弥散强化,达到细化晶粒与组织致密作用,提高了复合镀层的裂纹扩展抗力与显微硬度。
Pulse current（PC） electrodeposition was used to fabricate pure Ni and Ni-CeO2 nanostructure composite coatings under ultrasonic（U） field.Microstructure and mechanical property of the coatings were observed and characterized by means of environmental scanning electron microscopy（E-SEM）,transmission electron microscopy（TEM） and microhardness test.Effect of annealing treatment and CeO2 nanoparticles doping on microstructure,microhardness（HV0.2） and micro crack propagation of the coatings were also investigated.Experimental results indicate that the compact composite coatings with amorphous structure are prepared by pulse current deposition under ultrasonic field.Nano-sized CeO2 particles preferentially occupy or pile up in defects and micro-cracks of the coatings to prevent nucleation and propagation of cracks.After annealing at 500 ℃ for 2 h,the fine and dispersive NiCexO1-x（0x0.5） compound forms in the composite coatings can enhance its resistance of hot micro-cracks and microhardness greatly.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2012年第2期127-131,共5页
Transactions of Materials and Heat Treatment
基金
国家自然科学基金(50775113)
江苏省自然科学基金(BK2007201)
